The dictionary meaning of ´Retrofit´ is to modify machinery or a vehicle to incorporate changes and developments after manufacture. The other meaning of ´retrofitting´ is to carry out modifications in a machine so as to enhance its life span. In common parlance when a CNG or LPG kit is added to a running vehicle, the job undertaken is called ´Retrofitting.´ The same logic can be applied to cement plants or any equipment or machinery of a running manufacturing unit.
Today when the cement industry is operating at around 70 per cent of its capacity, no one is willing to incur any capital expenditure on the plant; on the other hand, some jobs are undertaken which will bring in some improvements or de-bottleneck the existing operations. As expressed by Kamal Kumar and Naiyar Azam of Holtec Consulting, "Success, and even survival, depends on how organisations prepare themselves to cope up with the environment. Manufacturers have minimal control on variables dominated by the external environment. The cement industry is in the grip of wide-sweeping environmental changes. Limited demand growth, industry consolidation, the spreading of areas of control of the MNCs, it´s all happening and at a very fast pace. Success, and even survival, depends on how organisations prepare themselves to manage the environment."
Kumar and Azam further emphasise the need for ´Operations Audit.´ It has been found as an effective tool for identifying the measures required to optimise the process operations and drawing action plans for exploring the hidden potential for enhancing the capacity through retrofitting route.
Process Audit helps in identifying the possibilities to upgrade the available equipment with optimum capital expenditure. A set of action plans are formulated based on identified improvement measures for implementation in the plant covering operational de-bottlenecking, establishing potential plant capacity, improving key performance indicators etc. According to Kumar, the main objective of the process optimisation study is to identify the inherent potential of the entire production process starting from mining operations to packing. Each unit operation is studied and analysed including plant stoppages in detail with an objective to identify the potential improvement areas for optimisation of operational practices for sustained operation covering energy conservation, capacity enhancement & environmental control. Moreover, in view of the fact that cement production is an energy intensive process, it is important for the cement production units to unleash the plant potential capacity so as to improve the capacity utilisation and lower the energy consumption, ensuring reduced unit cost of production.
While designing a plant, the engineers always have some margins in the kiln with a thought to add another stream of preheater and precalciner to increase the production at a later date with reasonable investment. The same thing can be said about finished grinding with some modifications in the grinding system like the size of compartments, modifications in separators, the output quantity and quality can be enhanced.
In fact, in a majority of plants, coolers are becoming bottlenecks to the increased production, as the kiln efficiencies have improved, capacities have gone up significantly but the coolers have remained the same, maybe due to space constraint in the existing plants. This is a good area for retrofitting.
In an article, Suchismita Bhattacharya and Pratap K Ghosh of Ercom Engineers Pvt. Ltd, while highlighting the changed norms of environment monitoring, also suggest the ways and means to tackle it. Recently, the norms for gaseous emissions from cement plants have undergone revision and the Ministry of Environment and Forests (MoEF) has amended the Environment (protection) Rules of 1986. The limits for NOX emissions for new plants are set at 600 mg/ Nm3 at 10% O2 (800 for older plants), and that for SO2 are set at 100 mg/Nm3 at 10% O2, dry basis. It will therefore be essential for producers to review their current operations so as to meet these new requirements, which are now quite stringent.
Most of the emissions into the environment are in the form of particulates, carbon dioxide, nitrogen oxides and sulphur oxides in exhaust gases. In some countries, mercury emissions are monitored and controlled. In cases where fuel or raw material quality lead to higher emissions, end of pipe control technology can be applied to meet emission norms, as suggested by Bhattacharya.
Sulphur is an input into the clinker burning process via raw materials and fuels. High values in the range of 600 to 800 mg/Nm3 have been observed.
It is really a big challenge for the industry, but at the same time, it is an opportunity for those in the consultancy profession to incorporate some changes in the existing plants to meet the changed norms of pollution by MoEF.
Meeting legislative and statutory demands is an additional benefit of retrofitting. Limiting greenhouse gas emissions, holding the temperature increase, reducing particulate emissions and SOx-NOx are some critical regulatory requirements that call for implementation of relevant retrofit projects at plants that are no longer compliant. Retrofitting projects will be on the increase in order to become compliant with newer, stricter safety regulations and standards.
Manoj Thakur of PENTA India, while writing on the same subject referred to COP21, the environmental conference organised by the UN recently in Paris. It has passed an international agreement applicable to all its 195 member countries to combat climate change. The agreement emphasises the need to hold the increase in the global average temperature to well below 2°C and to pursue efforts to limit it to 1.5°C, recognising that this would significantly reduce the risks and impact of climate change. This agreement will compel the cement manufacturers to execute relevant retrofit projects.
Thakur further says the general consensus of cement manufacturers worldwide is that retrofitting is the way to achieve specific energy consumption targets, optimise plant operations, maximise the production of blended cement, be compliant with environmental laws, etc. However, due to a variety of reasons, many plants are not able to implement a retrofit project. The services of a consultant can help cement manufacturers find the optimum technology for their particular operation and implement the project. Such services will develop the strategy to perform a feasibility study which will determine the approach and methodology, the execution schedule, keeping in mind the lowest capex and minimum downtime.